City libraries also have old assembly books. There are a wealth of ressources online, as my comrades have already illustrated, though they neglected to mention one important ressource. There are those online who trade in books, book warez. You can usually find anything from highly technical books to science-fiction novels. Your best bet is to hit irc.nullus.net and join #bookwarez. You'll find tons of assembly books for many architectures. Have fun and good luck.